Australian Federal Police (AFP) officers have charged six people over the country's biggest cocaine haul, which was discovered when authorities intercepted a yacht off the New South Wales coast.

Key points:

Six people arrested over record cocaine haul after yacht intercepted off NSW coast

Officers seized 1.4 tonnes with a street value of $312 million

Those arrested include four Australians, a New Zealander and a Swiss-Fijian dual national

More than 1.4 tonnes of the drug have been seized with an estimated street value in excess of $312 million.

The AFP said the arrests marked the end of a joint two-and-a-half-year investigation into an alleged drug network, described as a "trans-national" operation.

Police have alleged the yacht travelled from New Zealand last month to a ship in the South Pacific to pick up the drugs and bring them to Australia.

Border Force officers assisted in the arrests of the six suspects and the authorities expect to make more arrests.

At a joint media conference, Federal Justice Minister Michael Keenan confirmed it was the largest cocaine bust in Australia's history.

He said a 63-year-old New Zealand man and a 54-year-old Swiss-Fijian dual national were arrested on board the yacht.

Three men, aged 63, 62 and 66, were arrested on the NSW south coast, while a 32-year-old man was arrested in Sydney.

They are facing life in prison over the haul.

Mr Keenan said the operation had stopped a massive amount of cocaine from hitting the streets.

"We are seizing more drugs than ever before," he said.

"We are arresting more people than ever before and we are making sure that those that think they can target Australia, those that think they can target our illicit drug market, will be prosecuted."

Conflicting opinions on market impact

Mr Keenan said the drug seizure will likely drive up the price of cocaine.

"The impact we would assume it [taking the shipment out of circulation] would have is over time it will drive up the street price, which is already very high in Australia," Mr Keenan said.

"The Australian drug market continues to be highly lucrative for people who pedal in the misery of drugs.

"We pay an enormous price, more than any equivalent market in the world.

"A kilogram of cocaine in the US would be worth $26,000, here it can sell for up to $240,000.

However Australian Drug Law Reform Foundation president Dr Alex Wodak disagrees that the bust will have a major impact on the market.

He says large seizures have little bearing on price and availability.

"My own suspicion is that the increasing number of big seizures of cocaine probably more reflects growing supply, rather than increasing cleverness of law enforcement authorities at intercepting greater amounts," Dr Wodak said.